Research On The Direct Torque Control Of Permanent Magnet Synchronous Motor Based On Fuzzy Control

Permanent Magnet Synchronous Motors (PMSM) have high magnetic energy product. In the same volume, it can be smaller and lighter than asynchronous motor. In addition, it has stiff mechanical character and small rotor moment of inertia, so it is often used as servo motor under the condition of high torque response and high performance. In 1985, M. Depenbrock proposed the Direct Torque Control (DTC) method of asynchronous motor. DTC is very simple and has high control performance. After the successful application of DTC into servo system of asynchronous motor, DTC has become one of the pop research point of AC servo systems. But most researches of DTC are focused on asynchronous motors and until recent years some researches are implemented on the application of DTC into PMSM. For the research is still in its primary stage, many questions need to be solved. In this paper, the application of DTC into PMSM is discussed first, and then simulation of PMSM DTC is implemented using MATLAB software. Secondly, for the problem of torque ripple at low speed, a new DTC system based on fuzzy logic is proposed and simulation results show that the torque ripple is decreased drastically. The function of zero voltage vectors in PMSM DTC is different from that of asynchronous motor. The difference is discussed in the paper and a novel PMSM DTC system based on the fuzzy distribution of zero voltage vector strategy is proposed at last. Simulation results show that the new method decreases the torque ripple after using zero voltage vectors properly.